This invention relates to attitude seeking escape vehicles and more particularly to those vehicles which utilize atmospheric electrostatic potential to sense the vertical direction.
Escape vehicles commonly used in aircraft for effecting pilot rescue during emergency situations commonly have been catapult/rocket powered ejection seats. Ejection seats of this type usually leave the striken aircraft in a straight line trajectory relative to the aircraft and angled slightly to the rear from vertical when the aircraft is upright and level. They follow a generally upward slightly curved path relative to the aircraft to enable clearance of the vertical stabilizer by the pilot and ejection seat. No means are provided for altering the trajectory relative to the earth of the seat and pilot after the seat leaves the aircraft. A disproportionately high number of fatalities occur when pilots attempt to eject while the aircraft is in an inverted or unusual attitude at low altitudes. A military specification, MIL-S-18471D(AS) which is unclassified and available to the public, defines the military requirements of minimum altitude for safe ejection in various aircraft attitudes.
A pilot ejecting from an inverted aircraft below 190 feet above ground level, using an ejection seat having an initial straight line trajectory, is in serious danger of striking the ground before his parachute has time to open. Similarly, pilots ejecting at various roll or pitch attitudes other than inverted need proportionately less altitude to eject safely but in all cases, the greater the roll or pitch attitude of the aircraft relative to a horizontal plane, the greater will be the minimum altitude required for a safe ejection.